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Somborac T, Lutfullahoglu Bal G, Fatima K, Vihinen H, Paatero A, Jokitalo E, Paavilainen VO, Konovalova S. The subset of peroxisomal tail-anchored proteins do not reach peroxisomes via ER, instead mitochondria can be involved. PLoS One 2023; 18:e0295047. [PMID: 38039321 PMCID: PMC10691693 DOI: 10.1371/journal.pone.0295047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/13/2023] [Indexed: 12/03/2023] Open
Abstract
Peroxisomes are membrane-enclosed organelles with important roles in fatty acid breakdown, bile acid synthesis and biosynthesis of sterols and ether lipids. Defects in peroxisomes result in severe genetic diseases, such as Zellweger syndrome and neonatal adrenoleukodystrophy. However, many aspects of peroxisomal biogenesis are not well understood. Here we investigated delivery of tail-anchored (TA) proteins to peroxisomes in mammalian cells. Using glycosylation assays we showed that peroxisomal TA proteins do not enter the endoplasmic reticulum (ER) in both wild type (WT) and peroxisome-lacking cells. We observed that in cells lacking the essential peroxisome biogenesis factor, PEX19, peroxisomal TA proteins localize mainly to mitochondria. Finally, to investigate peroxisomal TA protein targeting in cells with fully functional peroxisomes we used a proximity biotinylation approach. We showed that while ER-targeted TA construct was exclusively inserted into the ER, peroxisome-targeted TA construct was inserted to both peroxisomes and mitochondria. Thus, in contrast to previous studies, our data suggest that some peroxisomal TA proteins do not insert to the ER prior to their delivery to peroxisomes, instead, mitochondria can be involved.
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Affiliation(s)
- Tamara Somborac
- HiLIFE, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | | - Kaneez Fatima
- HiLIFE, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Helena Vihinen
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Anja Paatero
- HiLIFE, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
| | | | - Svetlana Konovalova
- HiLIFE, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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2
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Vihinen H, Jokitalo E. Studying Golgi Structure and Function by Thin Section TEM. Methods Mol Biol 2022; 2557:141-159. [PMID: 36512215 DOI: 10.1007/978-1-0716-2639-9_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Here, we describe protocols for chemical fixation and flat embedding to study the Golgi structure by thin section transmission electron microscopy (TEM) and for 3,3'-diaminobenzidine (DAB) cytochemical staining and pre-embedding immunolabelling to localize specific Golgi proteins. Furthermore, we demonstrate how the Golgi morphology can be elucidated by classifying the Golgi membranes using Microscopy Image Browser-a software that provides anonymization, modelling, and annotation.
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Affiliation(s)
- Helena Vihinen
- Electron Microscopy Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland
| | - Eija Jokitalo
- Electron Microscopy Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, Helsinki, Finland.
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3
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Spang A, Mahendrarajah TA, Offre P, Stairs CW. Evolving perspective on the origin and diversification of cellular life and the virosphere. Genome Biol Evol 2022; 14:6537539. [PMID: 35218347 PMCID: PMC9169541 DOI: 10.1093/gbe/evac034] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2022] [Indexed: 11/14/2022] Open
Abstract
The tree of life (TOL) is a powerful framework to depict the evolutionary history of cellular organisms through time, from our microbial origins to the diversification of multicellular eukaryotes that shape the visible biosphere today. During the past decades, our perception of the TOL has fundamentally changed, in part, due to profound methodological advances, which allowed a more objective approach to studying organismal and viral diversity and led to the discovery of major new branches in the TOL as well as viral lineages. Phylogenetic and comparative genomics analyses of these data have, among others, revolutionized our understanding of the deep roots and diversity of microbial life, the origin of the eukaryotic cell, eukaryotic diversity, as well as the origin, and diversification of viruses. In this review, we provide an overview of some of the recent discoveries on the evolutionary history of cellular organisms and their viruses and discuss a variety of complementary techniques that we consider crucial for making further progress in our understanding of the TOL and its interconnection with the virosphere.
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Affiliation(s)
- Anja Spang
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, The Netherlands and 1790 AB Den Burg.,Department of Cell- and Molecular Biology, Science for Life Laboratory, Uppsala University, Sweden SE-75123, Uppsala
| | - Tara A Mahendrarajah
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, The Netherlands and 1790 AB Den Burg
| | - Pierre Offre
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, Utrecht University, The Netherlands and 1790 AB Den Burg
| | - Courtney W Stairs
- Department of Biology, Lund University, Sweden Sölvegatan 35, 223 62 Lund
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4
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Lecona-Valera AN, Rodriguez MH, Argotte-Ramos RS, Rodriguez MC. The chaperone micronemal protein Hsp70-1 from Plasmodium berghei ookinetes is shed during gliding on solid surface sustrata. Mol Biochem Parasitol 2021; 246:111428. [PMID: 34756988 DOI: 10.1016/j.molbiopara.2021.111428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 09/24/2021] [Accepted: 10/18/2021] [Indexed: 10/20/2022]
Abstract
Plasmodium the causative agent of malaria is a member of the phylum Apicomplexa, where all invasive forms have a substrate-dependent motility called gliding, key to malaria transmission. Gliding allows parasite host-cell recognition, binding, cell entry and trespassing the cytoplasm. In this process Plasmodium releases molecules from micronemes and the cell surface that are deposited on trails left behind on the substratum as the parasite progresses. Previously we identified the heat shock protein 70-1 (HSP 70-1) on the surface and micronemes of P. berghei ookinetes, the parasite form that invades the mosquito midgut. To investigate if this protein is shed of from the parasite during invasion, we searched HSP 70-1 in gliding trails deposited on a solid surface by P. berghei ookinetes.
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Affiliation(s)
- A N Lecona-Valera
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Ave. Universidad No. 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, CP 62100, México
| | - M H Rodriguez
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Ave. Universidad No. 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, CP 62100, México
| | - R S Argotte-Ramos
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Ave. Universidad No. 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, CP 62100, México
| | - M C Rodriguez
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Ave. Universidad No. 655, Col. Santa María Ahuacatitlán, Cuernavaca, Morelos, CP 62100, México.
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5
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Specific subdomain localization of ER resident proteins and membrane contact sites resolved by electron microscopy. Eur J Cell Biol 2021; 100:151180. [PMID: 34653930 DOI: 10.1016/j.ejcb.2021.151180] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/23/2021] [Accepted: 09/28/2021] [Indexed: 11/21/2022] Open
Abstract
The endoplasmic reticulum (ER) is a large, single-copy, membrane-bound organelle that comprises an elaborate 3D network of diverse structural subdomains, including highly curved tubules, flat sheets, and parts that form contacts with nearly every other organelle. The dynamic and complex organization of the ER poses a major challenge on understanding how its functioning - maintenance of the structure, distribution of its functions and communication with other organelles - is orchestrated. In this study, we resolved a unique localization profile within the ER network for several resident ER proteins representing a broad range of functions associated with the ER using immuno-electron microscopy and calculation of a relative labeling index (RLI). Our results demonstrated the effect of changing cellular environment on protein localization and highlighted the importance of correct protein expression level when analyzing its localization at subdomain resolution. We present new software tools for anonymization of images for blind analysis and for quantitative assessment of membrane contact sites (MCSs) from thin section transmission electron microscopy micrographs. The analysis of ER-mitochondria contacts suggested the presence of at least three different types of MCSs that responded differently to changes in cellular lipid loading status.
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6
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Specificities of exosome versus small ectosome secretion revealed by live intracellular tracking of CD63 and CD9. Nat Commun 2021; 12:4389. [PMID: 34282141 PMCID: PMC8289845 DOI: 10.1038/s41467-021-24384-2] [Citation(s) in RCA: 316] [Impact Index Per Article: 105.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 06/15/2021] [Indexed: 12/11/2022] Open
Abstract
Despite their roles in intercellular communications, the different populations of extracellular vesicles (EVs) and their secretion mechanisms are not fully characterized: how and to what extent EVs form as intraluminal vesicles of endocytic compartments (exosomes), or at the plasma membrane (PM) (ectosomes) remains unclear. Here we follow intracellular trafficking of the EV markers CD9 and CD63 from the endoplasmic reticulum to their residency compartment, respectively PM and late endosomes. We observe transient co-localization at both places, before they finally segregate. CD9 and a mutant CD63 stabilized at the PM are more abundantly released in EVs than CD63. Thus, in HeLa cells, ectosomes are more prominent than exosomes. By comparative proteomic analysis and differential response to neutralization of endosomal pH, we identify a few surface proteins likely specific of either exosomes (LAMP1) or ectosomes (BSG, SLC3A2). Our work sets the path for molecular and functional discrimination of exosomes and small ectosomes in any cell type. Extracellular vesicles (EVs) play a role in intercellular communication, however the precise biogenesis of different populations of EVs are not clear. Here, the authors follow the intracellular trafficking of two proteins before their secretion in EVs and report the biogenesis and protein markers of EV subtypes: ectosomes budding from the plasma membrane as well as exosomes from late endosomes.
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7
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Kumar D, Lak B, Suntio T, Vihinen H, Belevich I, Viita T, Xiaonan L, Vartiainen A, Vartiainen M, Varjosalo M, Jokitalo E. RTN4B interacting protein FAM134C promotes ER membrane curvature and has a functional role in autophagy. Mol Biol Cell 2021; 32:1158-1170. [PMID: 33826365 PMCID: PMC8351555 DOI: 10.1091/mbc.e20-06-0409] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The endoplasmic reticulum (ER) is composed of a controlled ratio of sheets and tubules, which are maintained by several proteins with multiple functions. Reticulons (RTNs), especially RTN4, and DP1/Yop1p family members are known to induce ER membrane curvature. RTN4B is the main RTN4 isoform expressed in nonneuronal cells. In this study, we identified FAM134C as a RTN4B interacting protein in mammalian, nonneuronal cells. FAM134C localized specifically to the ER tubules and sheet edges. Ultrastructural analysis revealed that overexpression of FAM134C induced the formation of unbranched, long tubules or dense globular structures composed of heavily branched narrow tubules. In both cases, tubules were nonmotile. ER tubulation was dependent on the reticulon homology domain (RHD) close to the N-terminus. FAM134C plays a role in the autophagy pathway as its level elevated significantly upon amino acid starvation but not during ER stress. Moreover, FAM134C depletion reduced the number and size of autophagic structures and the amount of ER as a cargo within autophagic structures under starvation conditions. Dominant-negative expression of FAM134C forms with mutated RHD or LC3 interacting region also led to a reduced number of autophagic structures. Our results suggest that FAM134C provides a link between regulation of ER architecture and ER turnover by promoting ER tubulation required for subsequent ER fragmentation and engulfment into autophagosomes.
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Affiliation(s)
| | - Behnam Lak
- Cell and Tissue Dynamics Research Program
| | | | - Helena Vihinen
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
| | - Ilya Belevich
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
| | | | - Liu Xiaonan
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | | | | | - Markku Varjosalo
- Molecular Systems Biology Research Group and Proteomics Unit, Institute of Biotechnology, Helsinki Institute of Life Science, University of Helsinki, 00014 Helsinki, Finland
| | - Eija Jokitalo
- Cell and Tissue Dynamics Research Program.,Electron Microscopy Unit, and
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8
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Rodriguez MC, Martínez-Barnetche J, Lecona-Valera AN, Téllez-Sosa J, Argotte-Ramos RS, Alvarado-Delgado A, Ovilla MT, Saldaña-Navor V, Rodriguez MH. Expression of Heat shock protein 70 (Hsp70-1) in Plasmodium berghei ookinetes and its participation in midgut mosquito infection. Mol Biochem Parasitol 2020; 240:111337. [PMID: 33147473 DOI: 10.1016/j.molbiopara.2020.111337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 10/22/2020] [Accepted: 10/28/2020] [Indexed: 10/23/2022]
Abstract
The heat shock protein family 70 (Hsp70) comprises chaperone proteins that play major multiple roles in Plasmodium asexual and sexual development. In this study, we analyzed the expression of Hsp70-1 in gametocytes, gametes, zygotes, and its participation in ookinete formation and their transition into oocysts. A monoclonal antibody against recombinant Hsp70-1 revealed its presence in zygotes and micronemes of ookinetes. Compared to wild type parasites, Hsp70-1 knockout ookinetes produced fewer oocysts in Plasmodium-susceptible Anopheles albimanus mosquitoes. This may indicate a defective transformation of ookinetes into oocysts in the absence of Hsp70-1. The presence of this protein in micronemes suggests its participation in mosquito infection, probably aiding to the adequate structural conformation of proteins in charge of motility, recognition and invasion of the insect midgut epithelium.
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Affiliation(s)
- Maria Carmen Rodriguez
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Jesús Martínez-Barnetche
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Alba N Lecona-Valera
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Juan Téllez-Sosa
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Rocio S Argotte-Ramos
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Alejandro Alvarado-Delgado
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Marbella T Ovilla
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Vianey Saldaña-Navor
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico
| | - Mario H Rodriguez
- Centro de Investigación Sobre Enfermedades Infecciosas, Instituto Nacional de Salud Pública, Av. Universidad 655, C. P. 62100, Cuernavaca, Morelos, Mexico.
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9
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Abdellatif MEA, Hipp L, Plessner M, Walther P, Knöll B. Indirect visualization of endogenous nuclear actin by correlative light and electron microscopy (CLEM) using an actin-directed chromobody. Histochem Cell Biol 2019; 152:133-143. [PMID: 31154480 PMCID: PMC6675784 DOI: 10.1007/s00418-019-01795-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/15/2019] [Indexed: 12/14/2022]
Abstract
Actin fulfills important cytoplasmic but also nuclear functions in eukaryotic cells. In the nucleus, actin modulates gene expression and chromatin remodeling. Monomeric (G-actin) and polymerized actin (F-actin) have been analyzed by fluorescence microscopy in the nucleus; however, the resolution at the ultrastructural level has not been investigated in great detail. We provide a first documentation of nuclear actin in mouse fibroblasts by electron microscopy (EM). For this, we employed correlative light and electron microscopy on the same section using actin-directed nanobodies recognizing endogenous monomeric and polymeric actin proteins (so-called nuclear Actin-chromobody-GFP; nAC-GFP). Indeed, using this strategy, we could identify actin proteins present in the nucleus. Here, immunogold-labeled actin proteins were spread throughout the entire nucleoplasm. Of note, nuclear actin was complementarily localized to DAPI-positive areas, the latter marking preferentially transcriptionally inactive heterochromatin. Since actin aggregates in rod structures upon cell stress including neurodegeneration, we analyzed nuclear actin at the ultrastructural level after DMSO or UV-mediated cell damage. In those cells the ratio between cytoplasmic and nuclear gold-labeled actin proteins was altered compared to untreated control cells. In summary, this EM analysis (i) confirmed the presence of endogenous nuclear actin at ultrastructural resolution, (ii) revealed the actin abundance in less chromatin-dense regions potentially reflecting more transcriptionally active euchromatin rather than transcriptionally inactive heterochromatin and (iii) showed an altered abundance of actin-associated gold particles upon cell stress.
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Affiliation(s)
- Mohamed E A Abdellatif
- Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Lisa Hipp
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Matthias Plessner
- Institute of Experimental and Clinical Pharmacology and Toxicology, University of Freiburg, Albertstr. 25, 79104, Freiburg, Germany
| | - Paul Walther
- Central Facility for Electron Microscopy, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany
| | - Bernd Knöll
- Institute of Physiological Chemistry, Ulm University, Albert-Einstein-Allee 11, 89081, Ulm, Germany.
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10
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Clarke NI, Royle SJ. FerriTag is a new genetically-encoded inducible tag for correlative light-electron microscopy. Nat Commun 2018; 9:2604. [PMID: 29973588 PMCID: PMC6031641 DOI: 10.1038/s41467-018-04993-0] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 05/24/2018] [Indexed: 01/20/2023] Open
Abstract
A current challenge is to develop tags to precisely visualize proteins in cells by light and electron microscopy. Here, we introduce FerriTag, a genetically-encoded chemically-inducible tag for correlative light-electron microscopy. FerriTag is a fluorescent recombinant electron-dense ferritin particle that can be attached to a protein-of-interest using rapamycin-induced heterodimerization. We demonstrate the utility of FerriTag for correlative light-electron microscopy by labeling proteins associated with various intracellular structures including mitochondria, plasma membrane, and clathrin-coated pits and vesicles. FerriTagging has a good signal-to-noise ratio and a labeling resolution of approximately 10 nm. We demonstrate how FerriTagging allows nanoscale mapping of protein location relative to a subcellular structure, and use it to detail the distribution and conformation of huntingtin-interacting protein 1 related (HIP1R) in and around clathrin-coated pits.
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Affiliation(s)
- Nicholas I Clarke
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK
| | - Stephen J Royle
- Centre for Mechanochemical Cell Biology, Warwick Medical School, Gibbet Hill Road, Coventry, CV4 7AL, UK.
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11
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Segmehl JS, Lauria A, Keplinger T, Berg JK, Burgert I. Tracking of Short Distance Transport Pathways in Biological Tissues by Ultra-Small Nanoparticles. Front Chem 2018; 6:28. [PMID: 29629368 PMCID: PMC5876598 DOI: 10.3389/fchem.2018.00028] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 02/05/2018] [Indexed: 11/16/2022] Open
Abstract
In this work, ultra-small europium-doped HfO2 nanoparticles were infiltrated into native wood and used as trackers for studying penetrability and diffusion pathways in the hierarchical wood structure. The high electron density, laser induced luminescence, and crystallinity of these particles allowed for a complementary detection of the particles in the cellular tissue. Confocal Raman microscopy and high-resolution synchrotron scanning wide-angle X-ray scattering (WAXS) measurements were used to detect the infiltrated particles in the native wood cell walls. This approach allows for simultaneously obtaining chemical information of the probed biological tissue and the spatial distribution of the integrated particles. The in-depth information about particle distribution in the complex wood structure can be used for revealing transport pathways in plant tissues, but also for gaining better understanding of modification treatments of plant scaffolds aiming at novel functionalized materials.
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Affiliation(s)
- Jana S Segmehl
- Wood Materials Science, Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zurich, Switzerland.,Bio-inspired Wood Materials, Applied Wood Materials, EMPA, Dübendorf, Switzerland
| | - Alessandro Lauria
- Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Zurich, Switzerland
| | - Tobias Keplinger
- Wood Materials Science, Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zurich, Switzerland.,Bio-inspired Wood Materials, Applied Wood Materials, EMPA, Dübendorf, Switzerland
| | - John K Berg
- Wood Materials Science, Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zurich, Switzerland.,Bio-inspired Wood Materials, Applied Wood Materials, EMPA, Dübendorf, Switzerland
| | - Ingo Burgert
- Wood Materials Science, Institute for Building Materials, Department of Civil, Environmental and Geomatic Engineering, ETH Zürich, Zurich, Switzerland.,Bio-inspired Wood Materials, Applied Wood Materials, EMPA, Dübendorf, Switzerland
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12
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Copping KJ, Ruiz-Diaz MD, Rutland CS, Mongan NP, Callaghan MJ, McMillen IC, Rodgers RJ, Perry VEA. Peri-conception and first trimester diet modifies reproductive development in bulls. Reprod Fertil Dev 2018; 30:703-720. [DOI: 10.1071/rd17102] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 09/19/2017] [Indexed: 01/21/2023] Open
Abstract
Nutritional perturbation during gestation alters male reproductive development in rodents and sheep. In cattle both the developmental trajectory of the feto–placental unit and its response to dietary perturbations is dissimilar to that of these species. This study examined the effects of dietary protein perturbation during the peri-conception and first trimester periods upon reproductive development in bulls. Nulliparous heifers (n = 360) were individually fed a high- or low-protein diet (HPeri and LPeri) from 60 days before conception. From 24 until 98 days post conception, half of each treatment group changed to the alternative post-conception high- or low-protein diet (HPost and LPost) yielding four treatment groups in a 2 × 2 factorial design. A subset of male fetuses (n = 25) was excised at 98 days post conception and fetal testis development was assessed. Reproductive development of singleton male progeny (n = 40) was assessed until slaughter at 598 days of age, when adult testicular cytology was evaluated. Low peri-conception diet delayed reproductive development: sperm quality was lowered during pubertal development with a concomitant delay in reaching puberty. These effects were subsequent to lower FSH concentrations at 330 and 438 days of age. In the fetus, the low peri-conception diet increased the proportion of seminiferous tubules and decreased blood vessel area in the testis, whereas low first trimester diet increased blood vessel number in the adult testis. We conclude that maternal dietary protein perturbation during conception and early gestation may alter male testis development and delay puberty in bulls.
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13
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Abstract
Transmission electron microscopy (TEM) can be used to successfully determine the structures of proteins. However, such studies are typically done ex situ after extraction of the protein from the cellular environment. Here we describe an application for nanodiamonds as targeted intensity contrast labels in biological TEM, using the nuclear pore complex (NPC) as a model macroassembly. We demonstrate that delivery of antibody-conjugated nanodiamonds to live mammalian cells using maltotriose-conjugated polypropylenimine dendrimers results in efficient localization of nanodiamonds to the intended cellular target. We further identify signatures of nanodiamonds under TEM that allow for unambiguous identification of individual nanodiamonds from a resin-embedded, OsO4-stained environment. This is the first demonstration of nanodiamonds as labels for nanoscale TEM-based identification of subcellular protein assemblies. These results, combined with the unique fluorescence properties and biocompatibility of nanodiamonds, represent an important step toward the use of nanodiamonds as markers for correlated optical/electron bioimaging.
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14
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Casanovas A, Salvany S, Lahoz V, Tarabal O, Piedrafita L, Sabater R, Hernández S, Calderó J, Esquerda JE. Neuregulin 1-ErbB module in C-bouton synapses on somatic motor neurons: molecular compartmentation and response to peripheral nerve injury. Sci Rep 2017; 7:40155. [PMID: 28065942 PMCID: PMC5220293 DOI: 10.1038/srep40155] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 12/02/2016] [Indexed: 12/30/2022] Open
Abstract
The electric activity of lower motor neurons (MNs) appears to play a role in determining cell-vulnerability in MN diseases. MN excitability is modulated by cholinergic inputs through C-type synaptic boutons, which display an endoplasmic reticulum-related subsurface cistern (SSC) adjacent to the postsynaptic membrane. Besides cholinergic molecules, a constellation of proteins involved in different signal-transduction pathways are clustered at C-type synaptic sites (M2 muscarinic receptors, Kv2.1 potassium channels, Ca2+ activated K+ [SK] channels, and sigma-1 receptors [S1R]), but their collective functional significance so far remains unknown. We have previously suggested that neuregulin-1 (NRG1)/ErbBs-based retrograde signalling occurs at this synapse. To better understand signalling through C-boutons, we performed an analysis of the distribution of C-bouton-associated signalling proteins. We show that within SSC, S1R, Kv2.1 and NRG1 are clustered in highly specific, non-overlapping, microdomains, whereas ErbB2 and ErbB4 are present in the adjacent presynaptic compartment. This organization may define highly ordered and spatially restricted sites for different signal-transduction pathways. SSC associated proteins are disrupted in axotomised MNs together with the activation of microglia, which display a positive chemotactism to C-bouton sites. This indicates that C-bouton associated molecules are also involved in neuroinflammatory signalling in diseased MNs, emerging as new potential therapeutic targets.
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Affiliation(s)
- Anna Casanovas
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Sara Salvany
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Víctor Lahoz
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Olga Tarabal
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Lídia Piedrafita
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Raimundo Sabater
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Sara Hernández
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Jordi Calderó
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
| | - Josep E. Esquerda
- Departament de Medicina Experimental, Patologia Neuromuscular Experimental, Facultat de Medicina, Universitat de Lleida/IRBLLEIDA, Av. Rovira Roure 80, 25198 Lleida, Catalonia, Spain
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15
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Stobart CC, Rostad CA, Ke Z, Dillard RS, Hampton CM, Strauss JD, Yi H, Hotard AL, Meng J, Pickles RJ, Sakamoto K, Lee S, Currier MG, Moin SM, Graham BS, Boukhvalova MS, Gilbert BE, Blanco JCG, Piedra PA, Wright ER, Moore ML. A live RSV vaccine with engineered thermostability is immunogenic in cotton rats despite high attenuation. Nat Commun 2016; 7:13916. [PMID: 28000669 PMCID: PMC5187593 DOI: 10.1038/ncomms13916] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 11/11/2016] [Indexed: 11/29/2022] Open
Abstract
Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization and there remains no pediatric vaccine. RSV live-attenuated vaccines (LAVs) have a history of safe testing in infants; however, achieving an effective balance of attenuation and immunogenicity has proven challenging. Here we seek to engineer an RSV LAV with enhanced immunogenicity. Genetic mapping identifies strain line 19 fusion (F) protein residues that correlate with pre-fusion antigen maintenance by ELISA and thermal stability of infectivity in live RSV. We generate a LAV candidate named OE4 which expresses line 19F and is attenuated by codon-deoptimization of non-structural (NS1 and NS2) genes, deletion of the small hydrophobic (SH) gene, codon-deoptimization of the attachment (G) gene and ablation of the secreted form of G. OE4 (RSV-A2-dNS1-dNS2-ΔSH-dGm-Gsnull-line19F) exhibits elevated pre-fusion antigen levels, thermal stability, immunogenicity, and efficacy despite heavy attenuation in the upper and lower airways of cotton rats.
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Affiliation(s)
- Christopher C. Stobart
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Christina A. Rostad
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Zunlong Ke
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Rebecca S. Dillard
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Cheri M. Hampton
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Joshua D. Strauss
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Hong Yi
- Robert P Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, Georgia 30322, USA
| | - Anne L. Hotard
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Jia Meng
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Raymond J. Pickles
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Kaori Sakamoto
- Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, Georgia 30602, USA
| | - Sujin Lee
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Michael G. Currier
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
| | - Syed M. Moin
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20852, USA
| | - Barney S. Graham
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland 20852, USA
| | | | - Brian E. Gilbert
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
| | | | - Pedro A. Piedra
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Elizabeth R. Wright
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
- Robert P Apkarian Integrated Electron Microscopy Core, Emory University, Atlanta, Georgia 30322, USA
| | - Martin L. Moore
- Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia 30322, USA
- Children's Healthcare of Atlanta, Atlanta, Georgia 30322, USA
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16
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Pastorek L, Sobol M, Hozák P. Colocalization coefficients evaluating the distribution of molecular targets in microscopy methods based on pointed patterns. Histochem Cell Biol 2016; 146:391-406. [PMID: 27460592 PMCID: PMC5037163 DOI: 10.1007/s00418-016-1467-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 01/28/2023]
Abstract
In biomedical studies, the colocalization is commonly understood as the overlap between distinctive labelings in images. This term is usually associated especially with quantitative evaluation of the immunostaining in fluorescence microscopy. On the other hand, the evaluation of the immunolabeling colocalization in the electron microscopy images is still under-investigated and biased by the subjective and non-quantitative interpretation of the image data. We introduce a novel computational technique for quantifying the level of colocalization in pointed patterns. Our approach follows the idea included in the widely used Manders' colocalization coefficients in fluorescence microscopy and represents its counterpart for electron microscopy. In presented methodology, colocalization is understood as the product of the spatial interactions at the single-particle (single-molecule) level. Our approach extends the current significance testing in the immunoelectron microscopy images and establishes the descriptive colocalization coefficients. To demonstrate the performance of the proposed coefficients, we investigated the level of spatial interactions of phosphatidylinositol 4,5-bisphosphate with fibrillarin in nucleoli. We compared the electron microscopy colocalization coefficients with Manders' colocalization coefficients for confocal microscopy and super-resolution structured illumination microscopy. The similar tendency of the values obtained using different colocalization approaches suggests the biological validity of the scientific conclusions. The presented methodology represents a good basis for further development of the quantitative analysis of immunoelectron microscopy data and can be used for studying molecular interactions at the ultrastructural level. Moreover, this methodology can be applied also to the other super-resolution microscopy techniques focused on characterization of discrete pointed structures.
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Affiliation(s)
- Lukáš Pastorek
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Margarita Sobol
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic.
- Microscopy Centre, Institute of Molecular Genetics ASCR v.v.i., Vídeňská 1083, 142 20, Prague 4, Czech Republic.
- Laboratory of Epigenetics of the Cell Nucleus, Division BIOCEV, Institute of Molecular Genetics of the ASCR v. v. i., Průmyslová 595, 252 50, Vestec, Czech Republic.
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17
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Abstract
This chapter describes advantages and limitations of imaging flow cytometry (IFC) based on Imagestream instrumentation using a hybrid approach of morphometric measurement and quantitation of multiparametric fluorescent intensities' distribution in cells and particles. Brief comparison is given of IFC with conventional flow cytometry and fluorescent microscopy. Some future directions of the IFC technology are described and discussed.
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Affiliation(s)
- Ivan A Vorobjev
- Department of Cell Biology and Histology, M.V. Lomonosov Moscow State University, Moscow, 119992, Russia.
- A.N. Belozersky Institute of Physico-Chemical Biology, M.V. Lomonosov Moscow State University, Moscow, 119992, Russia.
| | - Natasha S Barteneva
- Cellular and Molecular Medicine Program, Boston Childrens Hospital, Boston, MA, 02115, USA.
- Department of Pediatrics, Harvard Medical School, Boston, MA, 02115, USA.
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18
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Mayhew TM, Lucocq JM. From gross anatomy to the nanomorphome: stereological tools provide a paradigm for advancing research in quantitative morphomics. J Anat 2015; 226:309-21. [PMID: 25753334 DOI: 10.1111/joa.12287] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/20/2015] [Indexed: 01/08/2023] Open
Abstract
The terms morphome and morphomics are not new but, recently, a group of morphologists and cell biologists has given them clear definitions and emphasised their integral importance in systems biology. By analogy to other '-omes', the morphome refers to the distribution of matter within 3-dimensional (3D) space. It equates to the totality of morphological features within a biological system (virus, single cell, multicellular organism or populations thereof) and morphomics is the systematic study of those structures. Morphomics research has the potential to generate 'big data' because it includes all imaging techniques at all levels of achievable resolution and all structural scales from gross anatomy and medical imaging, via optical and electron microscopy, to molecular characterisation. As with other '-omics', quantification is an important part of morphomics and, because biological systems exist and operate in 3D space, precise descriptions of form, content and spatial relationships require the quantification of structure in 3D. Revealing and quantifying structural detail inside the specimen is achieved currently in two main ways: (i) by some form of reconstruction from serial physical or tomographic slices or (ii) by using randomly-sampled sections and simple test probes (points, lines, areas, volumes) to derive stereological estimates of global and/or individual quantities. The latter include volumes, surfaces, lengths and numbers of interesting features and spatial relationships between them. This article emphasises the value of stereological design, sampling principles and estimation tools as a template for combining with alternative imaging techniques to tackle the 'big data' issue and advance knowledge and understanding of the morphome. The combination of stereology, TEM and immunogold cytochemistry provides a practical illustration of how this has been achieved in the sub-field of nanomorphomics. Applying these quantitative tools/techniques in a carefully managed study design offers us a deeper appreciation of the spatiotemporal relationships between the genome, metabolome and morphome which are integral to systems biology.
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Affiliation(s)
- Terry M Mayhew
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham, UK; School of Medicine, University of St Andrews, St Andrews, UK
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19
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Mayhew TM. Quantitative immunocytochemistry at the ultrastructural level: a stereology-based approach to molecular nanomorphomics. Cell Tissue Res 2014; 360:43-59. [PMID: 25403623 DOI: 10.1007/s00441-014-2038-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/15/2014] [Indexed: 12/16/2022]
Abstract
Biological systems span multiple levels of structural organisation from the macroscopic, via the microscopic, to the nanoscale. Therefore, comprehensive investigation of systems biology requires application of imaging modalities that reveal structure at multiple resolution scales. Nanomorphomics is the part of morphomics devoted to the systematic study of functional morphology at the nanoscale and an important element of its achievement is the combination of immunolabelling and transmission electron microscopy (TEM). The ultimate goal of quantitative immunocytochemistry is to estimate numbers of target molecules (usually peptides, proteins or protein complexes) in biological systems and to map their spatial distributions within them. Immunogold cytochemistry utilises target-specific affinity markers (primary antibodies) and visualisation aids (e.g., colloidal gold particles or silver-enhanced nanogold particles) to detect and localise target molecules at high resolution in intact cells and tissues. In the case of post-embedding labelling of ultrathin sections for TEM, targets are localised as a countable digital readout by using colloidal gold particles. The readout comprises a spatial distribution of gold particles across the section and within the context of biological ultrastructure. The observed distribution across structural compartments (whether volume- or surface-occupying) represents both specific and non-specific labelling; an assessment by eye alone as to whether the distribution is random or non-random is not always possible. This review presents a coherent set of quantitative methods for testing whether target molecules exhibit preferential and specific labelling of compartments and for mapping the same targets in two or more groups of cells as their TEM immunogold-labelling patterns alter after experimental manipulation. The set also includes methods for quantifying colocalisation in multiple-labelling experiments and mapping absolute numbers of colloidal gold particles across compartments at specific positions within cells having a point-like inclusion (e.g., centrosome, nucleolus) and a definable vertical axis. Although developed for quantifying colloidal gold particles, the same methods can in principle be used to quantify other electron-dense punctate nanoparticles, including quantum dots.
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Affiliation(s)
- Terry M Mayhew
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, E Floor, Nottingham, NG7 2UH, UK,
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20
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Lucocq JM, Mayhew TM, Schwab Y, Steyer AM, Hacker C. Systems biology in 3D space--enter the morphome. Trends Cell Biol 2014; 25:59-64. [PMID: 25455351 DOI: 10.1016/j.tcb.2014.09.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Revised: 09/24/2014] [Accepted: 09/25/2014] [Indexed: 11/27/2022]
Abstract
Systems-based understanding of living organisms depends on acquiring huge datasets from arrays of genes, transcripts, proteins, and lipids. These data, referred to as 'omes', are assembled using 'omics' methodologies. Currently a comprehensive, quantitative view of cellular and organellar systems in 3D space at nanoscale/molecular resolution is missing. We introduce here the term 'morphome' for the distribution of living matter within a 3D biological system, and 'morphomics' for methods of collecting 3D data systematically and quantitatively. A sampling-based approach termed stereology currently provides rapid, precise, and minimally biased morphomics. We propose that stereology solves the 'big data' problem posed by emerging wide-scale electron microscopy (EM) and can establish quantitative links between the newer nanoimaging platforms such as electron tomography, cryo-EM, and correlative microscopy.
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Affiliation(s)
- John M Lucocq
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK.
| | - Terry M Mayhew
- School of Life Sciences, Queen's Medical Centre, University of Nottingham, Nottingham NG7 2UH, UK
| | - Yannick Schwab
- Electron Microscopy Core Facility, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Anna M Steyer
- Electron Microscopy Core Facility, Cell Biology and Biophysics Unit, European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Christian Hacker
- School of Medicine, University of St Andrews, St Andrews KY16 9TF, UK
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21
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Meriney SD, Umbach JA, Gundersen CB. Fast, Ca2+-dependent exocytosis at nerve terminals: shortcomings of SNARE-based models. Prog Neurobiol 2014; 121:55-90. [PMID: 25042638 DOI: 10.1016/j.pneurobio.2014.07.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Revised: 04/14/2014] [Accepted: 07/03/2014] [Indexed: 11/30/2022]
Abstract
Investigations over the last two decades have made major inroads in clarifying the cellular and molecular events that underlie the fast, synchronous release of neurotransmitter at nerve endings. Thus, appreciable progress has been made in establishing the structural features and biophysical properties of the calcium (Ca2+) channels that mediate the entry into nerve endings of the Ca2+ ions that trigger neurotransmitter release. It is now clear that presynaptic Ca2+ channels are regulated at many levels and the interplay of these regulatory mechanisms is just beginning to be understood. At the same time, many lines of research have converged on the conclusion that members of the synaptotagmin family serve as the primary Ca2+ sensors for the action potential-dependent release of neurotransmitter. This identification of synaptotagmins as the proteins which bind Ca2+ and initiate the exocytotic fusion of synaptic vesicles with the plasma membrane has spurred widespread efforts to reveal molecular details of synaptotagmin's action. Currently, most models propose that synaptotagmin interfaces directly or indirectly with SNARE (soluble, N-ethylmaleimide sensitive factor attachment receptors) proteins to trigger membrane fusion. However, in spite of intensive efforts, the field has not achieved consensus on the mechanism by which synaptotagmins act. Concurrently, the precise sequence of steps underlying SNARE-dependent membrane fusion remains controversial. This review considers the pros and cons of the different models of SNARE-mediated membrane fusion and concludes by discussing a novel proposal in which synaptotagmins might directly elicit membrane fusion without the intervention of SNARE proteins in this final fusion step.
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Affiliation(s)
- Stephen D Meriney
- Department of Neuroscience, Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Joy A Umbach
- Department of Molecular and Medical Pharmacology, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA
| | - Cameron B Gundersen
- Department of Molecular and Medical Pharmacology, UCLA David Geffen School of Medicine, Los Angeles, CA 90095, USA.
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22
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Romero AM, Renau-Piqueras J, Marín MP, Esteban-Pretel G. Chronic alcohol exposure affects the cell components involved in membrane traffic in neuronal dendrites. Neurotox Res 2014; 27:43-54. [PMID: 25022897 DOI: 10.1007/s12640-014-9484-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 06/13/2014] [Accepted: 07/01/2014] [Indexed: 01/09/2023]
Abstract
The specific traffic of the membrane components in neurons is a major requirement to establish and maintain neuronal domains-the axonal and the somatodendritic domains-and their polarized morphology. Unlike axons, dendrites contain membranous organelles, which are involved in the secretory pathway, including the endoplasmic reticulum, the Golgi apparatus and post-Golgi apparatus carriers, the cytoskeleton, and plasma membrane. A variety of molecules and factors are also involved in this process. Previous studies have shown that chronic alcohol exposure negatively affects several of these cell components, such as the Golgi apparatus or cytoskeleton in neurons. Yet very little information is available on the possible effects of this exposure on the remaining cell elements involved in intracellular trafficking in neurons, particularly in dendrites. By qualitative and quantitative electron microscopy, immunofluorescence and immunoblotting, we herein show that chronic exposure to moderate levels (30 mM) of ethanol in cultured neurons reduces the volume and surface density of the rough endoplasmic reticulum, and increases the levels of GRP78, a chaperone involved in endoplasmic reticulum stress. Ethanol also significantly diminishes the proportion of neurons that show an extension of Golgi into dendrites and dendritic Golgi outposts, a structure present exclusively in longer, thicker apical dendrites. Both Golgi apparatus types were also fragmented into a large number of cells. We also investigated the effect of alcohol on the levels of microtubule-based motor proteins KIF5, KIF17, KIFC2, dynein, and myosin IIb, responsible for transporting different cargoes in dendrites. Of these, alcohol differently affects several of them by lowering dynein and raising KIF5, KIFC2, and myosin IIb. These results, together with other previously published ones, suggest that practically all the protein trafficking steps in dendrites are altered to a greater or lesser extent by chronic alcohol exposure in neuronal cells, which may have negative repercussions for the development and maintenance of their polarized morphology and function.
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Affiliation(s)
- Ana M Romero
- Sección de Biología y Patología Celular, Centro de Investigación, Hospital Universitario ''La Fe'', Avenida Campanar 21, 46009, Valencia, Spain
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23
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Webster P, Webster A. Cryosectioning fixed and cryoprotected biological material for immunocytochemistry. Methods Mol Biol 2014; 1117:273-313. [PMID: 24357368 DOI: 10.1007/978-1-62703-776-1_13] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Immunocytochemistry for electron microscopy provides important information on the location and relative abundance of proteins inside cells. Gaining access to this information without extracting or disrupting the location of target proteins requires specialized preparation methods. Sectioning frozen blocks of chemically fixed and cryoprotected biological material is one method for obtaining immunocytochemical data. Once the cells or tissues are cut, the cryosections are thawed, mounted onto coated grids, and labeled with specific antibodies and colloidal gold probes. They are then embedded in a thin film of plastic containing a contrasting agent. Subcellular morphology can then be correlated with specific affinity labeling by examination in the transmission electron microscope (TEM). The major advantage of using thawed cryosections for immunolabeling is that the sections remain fully hydrated through the immunolabeling steps, reducing the possibility of dehydration-induced antigen modification. Modern technical advancements both in preparation protocols and equipment design make cryosectioning a routine and rapid approach for immunocytochemistry that may provide increased sensitivity for some antibodies.
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Affiliation(s)
- Paul Webster
- Center for Electron Microscopy and Microanalysis (CEMMA), University of Souther California, Los Angeles, CA, USA
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24
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Abstract
Technical improvements in electron microscopy, both instrumental and preparative, permit increasingly accurate analyses. Digital images for transmission electron microscopy (TEM) can be processed by software programs that automate tasks and create custom tools that allow for image enhancement for brightness, contrast and coloration; for creation of rectangular, ellipsoidal or irregular area selections; and for measurement of mean area and standard deviation. Sample preparation remains a source of error since organelles and spatial arrangements of macromolecules rapidly change after anoxia. Guidelines for maintaining consistency in preparation, examination and interpretation are presented for different electron microscopy (EM) modalities.
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Affiliation(s)
- N. F. Cheville
- Department of Veterinary Pathology, Iowa State University, Ames, IA, USA
| | - J. Stasko
- Microscopy Services, National Animal Disease Center, Ames, IA, USA
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25
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Esteban-Pretel G, Marín MP, Romero AM, Timoneda J, Ponsoda X, Ballestín R, Renau-Piqueras J. Polyphosphoinositide metabolism and Golgi complex morphology in hippocampal neurons in primary culture is altered by chronic ethanol exposure. Alcohol Alcohol 2012; 48:15-27. [PMID: 23118092 DOI: 10.1093/alcalc/ags117] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
AIMS Ethanol affects not only the cytoskeletal organization and activity, but also intracellular trafficking in neurons in the primary culture. Polyphosphoinositide (PPIn) are essential regulators of many important cell functions, including those mentioned, cytoskeleton integrity and intracellular vesicle trafficking. Since information about the effect of chronic ethanol exposure on PPIn metabolism in neurons is scarce, this study analysed the effect of this treatment on three of these phospholipids. METHODS Phosphatidylinositol (PtdIns) levels as well as the activity and/or levels of enzymes involved in their metabolism were analysed in neurons chronically exposed to ethanol. The levels of phospholipases C and D, and phosphatidylethanol formation were also assessed. The consequence of the possible alterations in the levels of PtdIns on the Golgi complex (GC) was also analysed. RESULTS We show that phosphatidylinositol (4,5)-bisphosphate and phosphatidylinositol (3,4,5)-trisphosphate levels, both involved in the control of intracellular trafficking and cytoskeleton organization, decrease in ethanol-exposed hippocampal neurons. In contrast, several kinases that participate in the metabolism of these phospholipids, and the level and/or activity of phospholipases C and D, increase in cells after ethanol exposure. Ethanol also promotes phosphatidylethanol formation in neurons, which can result in the suppression of phosphatidic acid synthesis and, therefore, in PPIn biosynthesis. This treatment also lowers the phosphatidylinositol 4-phosphate levels, the main PPIn in the GC, with alterations in their morphology and in the levels of some of the proteins involved in structure maintenance. CONCLUSIONS The deregulation of the metabolism of PtdIns may underlie the ethanol-induced alterations on different neuronal processes, including intracellular trafficking and cytoskeletal integrity.
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Affiliation(s)
- Guillermo Esteban-Pretel
- Corresponding author: Sección de Biología y Patología Celular, Centro de Investigación, Hospital Universitario La Fe, Avda. Campanar 21, Valencia, Spain.
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26
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Alcohol induces Golgi fragmentation in differentiated PC12 cells by deregulating Rab1-dependent ER-to-Golgi transport. Histochem Cell Biol 2012; 138:489-501. [PMID: 22614950 DOI: 10.1007/s00418-012-0970-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/08/2012] [Indexed: 10/28/2022]
Abstract
In the present study, we analyze the effects of ethanol on the Golgi structure and membrane transport in differentiated PC12 cells, which are used as a model of neurons. Chronic exposure to moderate doses of ethanol induces Golgi fragmentation, a common characteristic of many neurodegenerative diseases. Alcohol impaired the lateral linking of stacks without causing microtubule damage. Extensive immunocytochemical and western blot analyses of representative Golgi proteins showed that few, but important, proteins are significantly affected. Thus, alcohol exposure induced a significant ER-to-Golgi transport delay, the retention of the GTPase Rab1 in the Golgi membranes and the accumulation of tethering factor p115 in the cytosol. These modifications would explain the observed fragmentation. The amount of p115 and the stacking protein GRASP65 increased in alcohol-treated cells, which might be a mechanism to reverse Golgi damage. Importantly, the overexpression of GTP-tagged Rab1 but not of a dominant-negative Rab1 mutant, restored the Golgi morphology, suggesting that this protein is the main target of alcohol. Taken together, our results support the view that alcohol and neurodegenerative diseases such as Parkinson have similar effects on intracellular trafficking and provide new clues on the neuropathology of alcoholism.
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27
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Kobayashi K, Cheng D, Huynh M, Ratinac KR, Thordarson P, Braet F. Imaging fluorescently labeled complexes by means of multidimensional correlative light and transmission electron microscopy: practical considerations. Methods Cell Biol 2012; 111:1-20. [PMID: 22857920 DOI: 10.1016/b978-0-12-416026-2.00001-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
These days the common ground between structural biology and molecular biology continues to grow thanks to the biomolecular insights offered by correlative microscopy, even though the vision of combining insights from different imaging tools has been around for nearly four decades. The use of correlative imaging methods to dissect the cell's internal structure is progressing faster than ever as shown by the boom in the number of methodological approaches available for correlative microscopy studies, each designed to address a specific scientific question. In this chapter, we will present a relatively straightforward approach to combining information from fluorescence microscopy and electron microscopy at the supramolecular level. The method combines live-cell and/or confocal laser microscopy with classical sample preparation for transmission electron microscopy (TEM), thereby allowing the integration of dynamic details of subcellular processes with insights about the organelles and molecular machinery involved. We illustrate the applicability of this multidimensional correlative microscopy approach on cultured Caco-2 colorectal cancer cells exposed to fluorescently labeled cisplatin, and discuss how these methods can deepen our understanding of key cellular processes, such as drug uptake and cell fate.
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Affiliation(s)
- K Kobayashi
- Australian Centre for Microscopy & Microanalysis, The University of Sydney, NSW 2006, Australia
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